WO2023095876A1 - Dispositif d'analyse et procédé d'analyse - Google Patents

Dispositif d'analyse et procédé d'analyse Download PDF

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WO2023095876A1
WO2023095876A1 PCT/JP2022/043560 JP2022043560W WO2023095876A1 WO 2023095876 A1 WO2023095876 A1 WO 2023095876A1 JP 2022043560 W JP2022043560 W JP 2022043560W WO 2023095876 A1 WO2023095876 A1 WO 2023095876A1
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concentration
absorption
measuring
wavelength
calculated based
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PCT/JP2022/043560
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English (en)
Japanese (ja)
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貴明 花田
直希 名倉
享司 渋谷
健児 原
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株式会社堀場製作所
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Priority to CN202280070548.6A priority Critical patent/CN118140129A/zh
Publication of WO2023095876A1 publication Critical patent/WO2023095876A1/fr

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

Definitions

  • the present invention relates to analyzers and the like used for, for example, component analysis of gas.
  • measurement errors occur due to interfering components other than the target component to be measured, such as water (H 2 O) and/or carbon dioxide (CO 2 ) contained in the flue gas.
  • the absorption spectrum of the interfering component overlaps the absorption peak position of the component to be measured, resulting in an error in concentration determination.
  • Patent Document 1 is considered as a method for correcting the interference effect of the interference component on the component to be measured.
  • the present invention has been made in view of the problems as described above, and is characterized by the use of nitrogen monoxide, nitrogen dioxide, nitrous oxide, ammonia, ethane, formaldehyde, acetaldehyde, sulfur dioxide, methane, methanol or ethanol in combustion gas.
  • the main object of the present invention is to more effectively reduce the interference effect on the concentration of the component to be measured, which is at least one of the above, and to measure it with high accuracy.
  • the analyzer according to the present invention can detect nitrogen monoxide (NO), nitrogen dioxide (NO 2 ), nitrous oxide (N 2 O), ammonia (NH 3 ), ethane (C 2 H 6 ) in combustion gas. , formaldehyde (HCHO), acetaldehyde (CH 3 CHO), sulfur dioxide (SO 2 ), methane (CH 4 ), methanol (CH 3 OH) or ethanol (C 2 H 5 OH).
  • a laser light source for irradiating the combustion gas with reference light
  • a photodetector for detecting the intensity of the sample light transmitted through the combustion gas by the reference light
  • the photodetector a concentration calculation unit that calculates the concentration of the component to be measured based on the output signal, and the concentration calculation unit calculates the concentration of the nitric oxide between 5.24 and 5.26 ⁇ m when measuring the concentration of the nitric oxide.
  • the combustion gas includes exhaust gas discharged from an internal combustion engine, exhaust gas flowing through a flue, combustion gas generated by burning a sample, and the like.
  • the analyzer of the present invention modulates the oscillation wavelength of the laser light source, acquires the absorption modulation signal or absorption spectrum by collecting the absorption signals at each wavelength, and obtains the absorption modulation signal or absorption spectrum of the measurement target component and the interference component. Interference effects can be further reduced by utilizing differences in features. At that time, the wider the wavelength modulation range, the more differences in the characteristics of the absorption modulation signal or the absorption spectrum of the component to be measured and the interference component can be obtained. decreases, resulting in decreased measurement sensitivity. Therefore, considering the balance, it is desirable to set the wavelength modulation range between 0.1 and 2 cm ⁇ 1 in accordance with the shape of the absorption modulation signal or absorption spectrum of the component to be measured and the interference component.
  • the analyzer of the present invention uses a quantum cascade laser as a light source that oscillates laser light in the mid-infrared region where these gases exhibit the strongest absorption, and realizes a long optical path length by means of a multi-reflection cell or a resonance cell. Therefore, the above gases can be measured even at low concentrations of 100 ppm or less.
  • the long optical path length is 1 m or more and 100 m or less, preferably 1 m or more and 50 m or less, more preferably 5 m or more and 30 m or less, and even more preferably 5 m or more and 15 m or less.
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of low-concentration nitric oxide (NO) of 100 ppm or less, nitric oxide (NO) between 5.24 and 5.26 ⁇ m NO) absorption is used to calculate the concentration.
  • the laser light source emits laser light having an oscillation wavelength including wavelengths between 5.24 and 5.26 ⁇ m.
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of nitrogen dioxide (NO 2 ) at a low concentration of 100 ppm or less, nitrogen dioxide (NO 2 ) Calculate the concentration based on the absorption.
  • the laser light source emits laser light with an oscillation wavelength including wavelengths between 6.14 and 6.26 ⁇ m.
  • a wavelength between 6.14 and 6.26 ⁇ m, preferably a wavelength between 6.145 and 6.254 ⁇ m, more preferably 6.2322 ⁇ m or 6.2538 ⁇ m is the most intense of nitrogen dioxide (NO 2 ).
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of nitrous oxide (N 2 O) at a low concentration of 100 ppm or less. Concentrations are calculated based on nitrogen (N 2 O) uptake.
  • the laser light source emits laser light having an oscillation wavelength including wavelengths between 7.84 and 7.91 ⁇ m.
  • a wavelength between 7.84 and 7.91 ⁇ m, preferably a wavelength between 7.845 and 7.907, more preferably 7.8455 ⁇ m, 7.8509 ⁇ m, 7.8784 ⁇ m, or 7.9067 ⁇ m is sub-
  • N2O nitrogen oxides
  • H2O water
  • CH4 methane
  • C2H acetylene
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of ammonia (NH 3 ) at a low concentration of 100 ppm or less, ammonia (NH 3 ) between 9.38 and 9.56 ⁇ m Calculate the concentration based on the absorption of
  • the laser light source emits laser light with an oscillation wavelength including wavelengths between 9.38 and 9.56 ⁇ m.
  • a wavelength between 9.38-9.56 ⁇ m, preferably a wavelength between 9.384-9.557 ⁇ m, more preferably 9.3847 ⁇ m or 9.5566 ⁇ m has the strongest absorption of ammonia (NH 3 ).
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of ethane (C 2 H 6 ) at a low concentration of 100 ppm or less, ethane (C Concentrations are calculated based on the absorption of 2 H 6 ).
  • the laser light source emits laser light having an oscillation wavelength including wavelengths between 3.33 and 3.36 ⁇ m.
  • Wavelengths between 3.33 and 3.36 ⁇ m, preferably between 3.336 and 3.352 ⁇ m, more preferably between 3.3368 ⁇ m, 3.3482 ⁇ m, or 3.3519 ⁇ m are ethane (C 2 H 6 ) exists, the absorption intensity of the interfering components water ( H2O ), methane ( CH4 ) and/or ethylene ( C2H4 ) in the combustion gas in this wavelength region. are small and their interference effects are small. As a result, it is possible to improve the measurement accuracy of the concentration of ethane (C 2 H 6 ).
  • the absorption intensity of ethane (C 2 H 6 ) is smaller than that of the above wavelengths of 3.3368 ⁇ m, 3.3482 ⁇ m, or 3.3519 ⁇ m, but water (H 2 O) is present near this wavelength. , allowing simultaneous measurement of ethane (C 2 H 6 ) and water (H 2 O).
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of formaldehyde (HCHO) or acetaldehyde (CH 3 CHO) at a low concentration of 100 ppm or less. Concentrations are calculated based on the absorption of formaldehyde (HCHO) or acetaldehyde (CH 3 CHO).
  • the laser light source emits laser light with an oscillation wavelength including a wavelength between 5.65 and 5.67 ⁇ m. At a wavelength between 5.65 and 5.67 ⁇ m, preferably between 5.651 and 5.652 ⁇ m, more preferably at 5.6514 ⁇ m, there is one of the strongest absorption lines of formaldehyde (HCHO).
  • the absorption intensity of water (H 2 O) and/or ammonia (NH 3 ), which are interfering components in the combustion gas in this wavelength region, is small, and their interference effects are small.
  • the formaldehyde (HCHO) concentration measurement accuracy can be improved.
  • This wavelength also coincides with the strong absorption band of acetaldehyde (CH 3 CHO), enabling measurement of acetaldehyde (CH 3 CHO) or simultaneous measurement of formaldehyde (HCHO) and acetaldehyde (CH 3 CHO).
  • a wavelength between 5.65 and 5.67 ⁇ m, preferably a wavelength between 5.665 and 5.667 ⁇ m, and more preferably a wavelength of 5.6660 ⁇ m is more efficient for formaldehyde (HCHO) than the above wavelength of 5.6514 ⁇ m.
  • the absorption intensity is slightly smaller, the absorption intensity of water (H 2 O) is smaller and their interference effects are smaller.
  • the formaldehyde (HCHO) concentration measurement accuracy can be improved.
  • This wavelength also coincides with the strong absorption band of acetaldehyde (CH 3 CHO), enabling measurement of acetaldehyde (CH 3 CHO) or simultaneous measurement of formaldehyde (HCHO) and acetaldehyde (CH 3 CHO).
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of sulfur dioxide (SO 2 ) at a low concentration of 100 ppm or less. 2 ) Calculate the concentration based on the absorption.
  • the laser light source emits laser light with an oscillation wavelength including wavelengths between 7.38 and 7.42 ⁇ m.
  • a wavelength between 7.38-7.42 ⁇ m, preferably a wavelength between 7.385-7.417 ⁇ m, more preferably 7.3856 ⁇ m or 7.4163 ⁇ m is the most intense of sulfur dioxide (SO 2 ).
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of low-concentration methane (CH 4 ) of 100 ppm or less, methane (CH 4 ) between 7.50 and 7.54 ⁇ m Calculate the concentration based on the absorption of
  • the laser light source emits laser light having an oscillation wavelength including wavelengths between 7.50 and 7.54 ⁇ m. At a wavelength between 7.50 and 7.54 ⁇ m, preferably between 7.503 and 7.504 ⁇ m, more preferably at 7.5035 ⁇ m, there is one of the strongest absorption lines of methane (CH 4 ).
  • a wavelength between 7.50 and 7.54 ⁇ m, preferably a wavelength between 7.535 and 7.536 ⁇ m, more preferably a wavelength of 7.5354 ⁇ m is approximately equivalent to the wavelength of 7.5035 ⁇ m described above for methane (CH 4 ), which are the interfering components in the combustion gas in this wavelength region: water ( H2O ), sulfur dioxide ( SO2 ), acetylene ( C2H2 ), and/or nitrous oxide (N 2 O) have smaller absorption strengths and their interference effects are smaller. As a result, it is possible to improve the measurement accuracy of the concentration of methane (CH 4 ).
  • the analyzer of the present invention uses a multi-reflection cell or the like to measure the concentration of methanol (CH 3 OH) or ethanol (C 2 H 5 OH) at a low concentration of 100 ppm or less. Concentrations are calculated based on the absorption of methanol (CH 3 OH) or ethanol (C 2 H 5 OH) between .47 ⁇ m.
  • the laser light source emits laser light having an oscillation wavelength including wavelengths between 9.45 and 9.47 ⁇ m.
  • a wavelength between 9.45 and 9.47 ⁇ m, preferably between 9.467 and 9.468 ⁇ m, more preferably 9.4671 ⁇ m, is one of the strongest absorption lines of methanol (CH OH ).
  • the absorption intensity of ethylene (C 2 H 4 ), ammonia (NH 3 ), and/or carbon dioxide (CO 2 ), which are present and are interference components in the combustion gas in this wavelength range, is small, and their interference effects are small. .
  • This wavelength also coincides with the strong absorption band of ethanol ( C2H5OH ), so the measurement of ethanol ( C2H5OH ) or methanol ( CH3OH ) and ethanol ( C2H5OH ) can be measured simultaneously.
  • a wavelength between 9.45 and 9.47 ⁇ m, preferably a wavelength between 9.455 and 9.456 ⁇ m, more preferably a wavelength of 9.4557 ⁇ m is approximately equivalent to the above 9.4671 ⁇ m methanol (CH 3 OH ) or ethanol (C 2 H 5 OH), which are interfering components in the combustion gas in this wavelength region, ethylene (C 2 H 4 ), ammonia (NH 3 ), and/or carbon dioxide (CO 2 ) are smaller and their interference effects are smaller.
  • CH 3 OH methanol
  • CO 2 carbon dioxide
  • the analysis method according to the present invention is a measurement target component that is at least one of nitrogen monoxide, nitrogen dioxide, nitrous oxide, ammonia, ethane, formaldehyde, acetaldehyde, sulfur dioxide, methane, methanol, or ethanol in combustion gas.
  • the concentration is calculated based on the absorption at the absorption wavelength between 5.24 and 5.26 ⁇ m, and the concentration of the nitrogen dioxide
  • the concentration is calculated based on the absorption at absorption wavelengths between 6.14 and 6.26 ⁇ m, and when measuring the concentration of nitrous oxide, 7.84 to 7.91 ⁇ m
  • the concentration of ammonia is measured, the concentration is calculated based on the absorption at the absorption wavelength between 9.38 and 9.56 ⁇ m, and the concentration of ethane is calculated based on the absorption at the absorption wavelength between
  • the concentration is calculated based on the absorption at the absorption wavelength between 3.33 and 3.36 ⁇ m, and when measuring the concentration of the formaldehyde or the acetaldehyde, 5.65 to 5.
  • the concentration is calculated based on the absorption at an absorption wavelength between 7.50 and 7.54 ⁇ m, and when measuring the concentration of methanol or ethanol, the concentration is 9.45 to 9.45 ⁇ m.
  • the concentration is calculated based on absorption at absorption wavelengths between 9.47 ⁇ m.
  • the component to be measured which is at least one of nitrogen monoxide, nitrogen dioxide, nitrous oxide, ammonia, ethane, formaldehyde, acetaldehyde, sulfur dioxide, methane, methanol or ethanol in combustion gas can be measured with high accuracy.
  • FIG. 1 is an overall schematic diagram of an analysis device according to an embodiment of the present invention
  • FIG. It is a functional block diagram of the signal processing device in the same embodiment.
  • FIG. 4 is a diagram showing drive current (voltage) and modulation signal in pseudo continuous oscillation;
  • FIG. 4 is a schematic diagram showing a method of modulating a laser oscillation wavelength in the same embodiment;
  • 5 is a time-series graph showing an example of oscillation wavelength, light intensity I(t), logarithmic intensity L(t), feature signal F i (t), and correlation value S i (t) in the same embodiment.
  • FIG. 4 is a diagram showing drive current (voltage) and modulation signal in pseudo continuous oscillation
  • FIG. 4 is a schematic diagram showing a method of modulating a laser oscillation wavelength in the same embodiment
  • 5 is a time-series graph showing an example of oscillation wavelength, light intensity I(t), logarithmic intensity L(t), feature signal F i (t), and correlation value S i (t)
  • FIG. 4 is a diagram showing wavelength shift and modulation width shift in an intensity-related signal (absorption signal); 4 is a graph showing (a) wavelength correction relational data and (b) modulation correction relational data in the same embodiment. 4 is a lookup table showing (a) wavelength correction relational data and (b) modulation correction relational data in the same embodiment.
  • FIG. 10 is a diagram showing a conceptual diagram of concentration calculation using a single correlation value and a measured correlation value in the same embodiment; It is a functional block diagram of a signal processing device in a modified embodiment.
  • FIG. 11 is an overall schematic diagram of an analysis device according to a modified embodiment;
  • FIG. 4 is a schematic diagram showing spectral changes due to coexistence effects and spectral changes due to pressure changes;
  • the analysis device 100 of the present embodiment is a concentration measurement device that measures the concentration of a measurement target component contained in a combustion gas such as a combustion gas or a combustion exhaust gas, or a sample gas such as a process gas.
  • a combustion gas such as a combustion gas or a combustion exhaust gas
  • a sample gas such as a process gas.
  • the gas being burned is the gas being burned in an internal combustion engine such as an automobile, an external combustion engine, an industrial furnace, an incinerator, a turbine, or a power plant, etc.
  • the combustion exhaust gas is an internal combustion engine such as an automobile, It is a post-combustion gas discharged from an external combustion engine, an industrial furnace, an incinerator, a turbine, or a power plant.
  • Process gas refers to gas in chemical plants such as petrochemical, coal chemical, natural gas chemical, petroleum refining, methanation, and gasification furnaces. It includes gas or gas produced in a chemical plant.
  • the analyzer 100 of the present embodiment is connected to an introduction channel for introducing a sampling gas into the analyzer 100, and is also connected to a discharge channel for discharging the gas analyzed by the analyzer 100. It is A pump for introducing the sampling gas into the analyzer 100 is provided in the introduction channel or the discharge channel.
  • the introduction channel may be configured to directly sample the exhaust gas from an exhaust pipe or the like, or may be configured to introduce the exhaust gas from a bag in which the exhaust gas is collected. It may be configured to introduce exhaust gas diluted by a dilution device such as a volume sampler.
  • the cell 1 is made of a transparent material such as quartz, calcium fluoride, barium fluoride, etc., which hardly absorbs light in the absorption wavelength band of the component to be measured, and has a light entrance and a light exit. Although not shown, the cell 1 is provided with an inlet port for introducing gas into the interior and an outlet port for discharging the internal gas. introduced into a transparent material such as quartz, calcium fluoride, barium fluoride, etc., which hardly absorbs light in the absorption wavelength band of the component to be measured, and has a light entrance and a light exit. Although not shown, the cell 1 is provided with an inlet port for introducing gas into the interior and an outlet port for discharging the internal gas. introduced into a transparent material such as quartz, calcium fluoride, barium fluoride, etc., which hardly absorbs light in the absorption wavelength band of the component to be measured, and has a light entrance and a light exit. Although not shown, the cell 1 is provided with an inlet port for introducing gas into
  • the semiconductor laser 2 here is a quantum cascade laser (QCL), which is a type of semiconductor laser 2, and oscillates mid-infrared (4 to 12 ⁇ m) laser light.
  • QCL quantum cascade laser
  • This semiconductor laser 2 is capable of modulating (changing) the oscillation wavelength by a given current (or voltage). Note that other types of lasers may be used as long as the oscillation wavelength is variable, and the temperature may be changed to change the oscillation wavelength.
  • the temperature controller 3 adjusts the temperature of the semiconductor laser 2, and uses a thermoelectric conversion element such as a Peltier element.
  • the temperature control unit 3 of the present embodiment has a semiconductor laser 2 and a temperature sensor (not shown) for detecting the temperature of the semiconductor laser 2 mounted on the heat absorption surface, which is the upper surface, and a temperature sensor (not shown) for detecting the temperature of the semiconductor laser 2.
  • a heat sink (not shown) such as radiation fins is provided.
  • the temperature control section 3 adjusts the temperature of the semiconductor laser 2 by controlling the applied DC voltage (DC current) according to a target temperature given by a temperature control control section 72 which will be described later.
  • the temperature sensor 4 detects the ambient temperature of the semiconductor laser 2. Here, it detects the temperature in the atmosphere inside the package housing the semiconductor laser and the temperature control unit 3, or the ambient temperature outside the package. .
  • the photodetector 5 here uses a thermal type such as a thermopile that is relatively inexpensive, but other types such as quantum type such as HgCdTe, InGaAs, InAsSb, or PbSe with good responsiveness are used.
  • a photoelectric element may also be used.
  • the signal processing device 6 includes at least one of an analog electric circuit consisting of a buffer, an amplifier, etc., a digital electric circuit consisting of a CPU, a memory, etc., and an AD converter, a DA converter, etc. that mediate between these analog/digital electric circuits.
  • a control unit 7 for controlling the semiconductor laser 2 and the temperature control unit 3 as shown in FIG. also, it functions as a signal processing section 8 that receives an output signal from the photodetector 5 and calculates the concentration of the component to be measured by arithmetically processing the value.
  • the control unit 7 has a light source control unit 71 that controls the oscillation and modulation width of the semiconductor laser 2 and a temperature control unit 72 that controls the temperature control unit 3 to a predetermined temperature.
  • the light source control unit 71 controls a current source (or voltage source) that drives the semiconductor laser 2 by outputting a current (or voltage) control signal. Specifically, as shown in FIG. 3, the light source control unit 71 applies a drive current (or drive voltage) for wavelength modulation to a predetermined frequency, in addition to the drive current (or drive voltage) for causing the semiconductor laser 2 to pulse-oscillate. , and the oscillation wavelength of the laser light output from the semiconductor laser 2 is modulated at a predetermined frequency with respect to the center wavelength. As a result, the semiconductor laser 2 emits modulated light modulated at a predetermined modulation frequency.
  • the light source control unit 71 changes the driving current in a triangular waveform, and modulates the oscillation wavelength in a triangular waveform (see “Oscillation wavelength" in FIG. 5).
  • the driving current is modulated by another function so that the oscillation wavelength becomes triangular.
  • the oscillation wavelength of the laser beam is modulated with the peak of the light absorption spectrum of the component to be measured as the central wavelength.
  • the light source control unit 71 may change the drive current in a sine wave, sawtooth wave, or any function, and modulate the oscillation wavelength in a sine wave, sawtooth wave, or any function.
  • the analyzer 100 detects nitrogen monoxide (NO), nitrogen dioxide (NO 2 ), nitrous oxide (N 2 O), ammonia (NH 3 ), ethane (C 2 H 6 ), formaldehyde in the combustion gas. (HCHO), acetaldehyde ( CH3CHO ) sulfur dioxide ( SO2 ), methane ( CH4 ), methanol ( CH3OH ) or ethanol ( C2H5OH ), when measuring the concentration of at least one of
  • the light source controller 71 modulates the semiconductor laser 2 so that the wavelength modulation range is as follows.
  • the semiconductor laser 2 is appropriately selected to emit modulated light modulated within the following wavelength modulation range.
  • the light source control unit 71 sets the wavelength modulation range of the laser light to include wavelengths between 5.24 and 5.26 ⁇ m. modulate. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so as to preferably include a wavelength of 5.245 to 5.247 ⁇ m, more preferably a wavelength of 5.2462 ⁇ m. Such modulation can reduce the interfering effects of water (H 2 O), carbon dioxide (CO 2 ) and/or ethylene (C 2 H 4 ) and low concentrations of nitric oxide (NO). can improve the measurement accuracy of the concentration of
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 6.14 and 6.26 ⁇ m. modulate. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so that it preferably includes a wavelength of 6.145 to 6.254 ⁇ m, more preferably a wavelength of 6.2322 ⁇ m or 6.2538 ⁇ m. . Such modulation can reduce the interfering effects of water (H 2 O) and/or ammonia (NH 3 ) and improve the measurement accuracy of low-concentration nitrogen dioxide (NO 2 ) concentrations. can be done.
  • modulation can reduce the interfering effects of water (H 2 O) and/or ammonia (NH 3 ) and improve the measurement accuracy of low-concentration nitrogen dioxide (NO 2 ) concentrations. can be done.
  • the light source control unit 71 sets the wavelength modulation range of the laser light to include wavelengths between 7.84 and 7.91 ⁇ m. modulate as follows. Specifically, the light source control unit 71 sets the wavelength modulation range of the laser light to 7, preferably a wavelength between 7.845 and 7.907, more preferably 7.8455 ⁇ m, 7.8509 ⁇ m, 7.8784 ⁇ m, or 7.8455 ⁇ m, 7.8509 ⁇ m, and 7.8784 ⁇ m. Modulate to include the wavelength of 9067 ⁇ m.
  • Such modulation can reduce the interfering effects of water (H 2 O), methane (CH 4 ) and/or acetylene (C 2 H 2 ) and low concentrations of nitrous oxide (N 2 O). ) can improve the measurement accuracy of the concentration.
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so as to include wavelengths between 9.38 and 9.56 ⁇ m.
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so that it preferably includes a wavelength between 9.384 and 9.557 ⁇ m, more preferably a wavelength of 9.3847 ⁇ m or 9.5566 ⁇ m. .
  • the interfering effects of water ( H2O ), carbon dioxide ( CO2 ) and/or ethylene ( C2H4 ) can be reduced, and low concentrations of ammonia ( NH3 ) can be reduced . Concentration measurement accuracy can be improved.
  • the light source controller 71 sets the wavelength modulation range of the laser light to include wavelengths between 3.33 and 3.36 ⁇ m. modulate to Specifically, the light source control unit 71 determines that the wavelength modulation range of the laser light is preferably a wavelength between 3.336 and 3.352 ⁇ m, more preferably a wavelength of 3.3368 ⁇ m, 3.3482 ⁇ m, or 3.3519 ⁇ m. is modulated to include Such modulation can reduce the interfering effects of water (H 2 O), methane (CH 4 ) and/or ethylene (C 2 H 4 ), and low concentrations of ethane (C 2 H 6 ). can improve the measurement accuracy of the concentration of
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so as to include wavelengths between 5.65 and 5.67 ⁇ m. . Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so as to preferably include a wavelength between 5.651 and 5.652, more preferably a wavelength of 5.6514 ⁇ m. Such modulation can reduce the interfering effects of water (H 2 O) and/or ammonia (NH 3 ) and improve the measurement accuracy of low-concentration formaldehyde (HCHO) concentrations. . In addition, since these wavelengths also coincide with the strong absorption band of acetaldehyde (CH 3 CHO), simultaneous measurement of formaldehyde (HCHO) and acetaldehyde (CH 3 CHO) is possible.
  • HCHO acetaldehyde
  • the light source control unit 71 can also modulate the wavelength modulation range of the laser light so as to preferably include a wavelength between 5.665 and 5.667 ⁇ m, more preferably a wavelength of 5.6660 ⁇ m.
  • the absorption intensity of formaldehyde (HCHO) is slightly lower than the wavelength of 5.6514 ⁇ m, but the absorption intensity of water (H 2 O) is smaller, and their interference effects are smaller. As a result, the formaldehyde (HCHO) concentration measurement accuracy can be improved.
  • This wavelength also coincides with the strong absorption band of acetaldehyde (CH 3 CHO), enabling measurement of acetaldehyde (CH 3 CHO) or simultaneous measurement of formaldehyde (HCHO) and acetaldehyde (CH 3 CHO).
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 7.38 and 7.42 ⁇ m. modulate. Specifically, the light source control unit 71 preferably modulates the wavelength modulation range of the laser light to include a wavelength of 7.385 to 7.417 ⁇ m, more preferably a wavelength of 7.3856 ⁇ m or 7.4163 ⁇ m. .
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so as to include wavelengths between 7.50 and 7.54 ⁇ m.
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so as to preferably include a wavelength of 7.503 to 7.504 ⁇ m, more preferably a wavelength of 7.5035 ⁇ m.
  • Such modulation can reduce the interfering effects of water ( H2O ), sulfur dioxide ( SO2 ), acetylene ( C2H2 ) and/or nitrous oxide ( N2O ), It is possible to improve the measurement accuracy of the low-concentration methane (CH 4 ) concentration.
  • by modulating to include 7.5035 ⁇ m there is an absorption line of water (H 2 O) near this wavelength, and simultaneous measurement of methane (CH 4 ) and water (H 2 O) is possible. becomes.
  • the light source control unit 71 can also modulate the wavelength modulation range of the laser light so as to preferably include a wavelength between 7.535 and 7.536 ⁇ m, more preferably a wavelength of 7.5354 ⁇ m.
  • the absorption intensity of methane (CH 4 ) is almost equivalent to the wavelength of 7.5035 ⁇ m above, and the interference components in the combustion gas in this wavelength range are water (H 2 O), sulfur dioxide (SO 2 ), acetylene ( C 2 H 2 ) and/or nitrous oxide (N 2 O) have smaller absorption intensities and their interfering effects are smaller. As a result, it is possible to improve the measurement accuracy of the concentration of methane (CH 4 ).
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 9.45 and 9.47 ⁇ m. modulate. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so as to preferably include a wavelength between 9.467 and 9.468 ⁇ m, more preferably a wavelength of 9.4671 ⁇ m. By modulating in this way, the interfering effects of ethylene ( C2H4 ), ammonia ( NH3 ) and/or carbon dioxide ( CO2 ) can be reduced, and low concentrations of methanol ( CH3OH ) can be reduced. Concentration measurement accuracy can be improved. These wavelengths also coincide with the strong absorption band of ethanol (C 2 H 5 OH), allowing simultaneous measurement of methanol (CH 3 OH) and ethanol (C 2 H 5 OH).
  • the light source control unit 71 can also modulate the wavelength modulation range of the laser light so as to preferably include a wavelength between 9.455 and 9.456 ⁇ m, more preferably a wavelength of 9.4557 ⁇ m.
  • ethylene (C 2 H 4 ) which has an absorption intensity of methanol (CH 3 OH) or ethanol (C 2 H 5 OH) approximately equivalent to the above 9.4671 ⁇ m, and is an interference component in the combustion gas in this wavelength region; Ammonia (NH 3 ) and/or carbon dioxide (CO 2 ) have lower absorption intensities and their interference effects are smaller.
  • NH 3 methanol
  • CO 2 carbon dioxide
  • the analyzer 100 detects carbon dioxide (CO 2 ), carbon monoxide (CO), ethylene (C 2 H 4 ), ammonia (NH 3 ), ethane (C 2 H 6 ), water (H 2 O), acetylene (C 2 H 2 ), methane (CH 4 ), ammonia (NH 3 ), and methanol (CH 3 OH).
  • the semiconductor laser 2 is modulated within the wavelength modulation range.
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 4.23 and 4.24 ⁇ m. modulate. Specifically, the light source control unit 71 preferably controls the wavelength modulation range of the laser light to be between 4.234 ⁇ m and 4.238 ⁇ m, or between 4.235 ⁇ m and 4.238 ⁇ m, more preferably between 4.2347 ⁇ m and 4.2347 ⁇ m. Modulate to include the wavelength of 2371 ⁇ m.
  • the light source control unit 71 determines that the wavelength modulation range of the laser light includes wavelengths between 4.34 and 4.35 ⁇ m. modulate as follows. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so that it preferably includes a wavelength between 4.342 and 4.347 ⁇ m, more preferably a wavelength of 4.3428 ⁇ m or 4.3469 ⁇ m. .
  • the light source control unit 71 sets the wavelength modulation range of the laser light between 4.59 and 4.61 ⁇ m, or between 4.59 and 4.59 ⁇ m. 4. Modulate to include the 60 ⁇ m wavelength. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so that it preferably includes a wavelength between 4.594 and 4.604 ⁇ m, more preferably a wavelength of 4.5950 ⁇ m or 4.6024 ⁇ m. .
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 5.89 and 6.12 ⁇ m. modulate. Specifically, the light source control unit 71 preferably modulates the wavelength modulation range of the laser light to include a wavelength of 5.896 to 5.934 ⁇ m, more preferably 5.8965 ⁇ m or 5.9353 ⁇ m. .
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so as to preferably include a wavelength of 6.046 to 6.114 ⁇ m, more preferably a wavelength of 6.0486 ⁇ m or 6.1138 ⁇ m. can also By modulating in this way, the interfering effects of methane ( CH4 ), ethylene ( C2H4 ) and/or ethane ( C2H6 ) can be reduced, and high concentrations of methane ( CH4 ), The measurement accuracy of dilute water ( H2O ) concentrations in process gases containing ethylene ( C2H4 ) and/or ethane ( C2H6 ) can be improved.
  • the light source control unit 71 sets the wavelength modulation range of the laser light between 7.56 ⁇ m and 7.66 ⁇ m. Modulate to include wavelengths between 7.81 ⁇ m, between 7.27-7.24 ⁇ m, or between 7.25-7.81 ⁇ m.
  • the light source control unit 71 preferably determines that the wavelength modulation range of the laser light is between 7.378 and 7.638 ⁇ m, between 7.378 and 7.603 ⁇ m, between 7.378 and 7.420 ⁇ m, a wavelength between 7.430 and 7.603 ⁇ m, between 7.430 and 7.638 ⁇ m, between 7.629 and 7.683 ⁇ m, or between 7.594 and 7.651 ⁇ m, more preferably 7.5966 ⁇ m, Modulate to include wavelengths of 7.6233 ⁇ m or 7.6501 ⁇ m.
  • the light source control unit 71 preferably controls the wavelength modulation range of the laser light to include wavelengths between 7.566 and 7.634 ⁇ m, more preferably 7.5698 ⁇ m, 7.6231 ⁇ m, or 7.6367 ⁇ m. It can also be modulated. By modulating in this way, the interfering effects of methane ( CH4 ), ethylene ( C2H4 ) and/or ethane ( C2H6 ) can be reduced, and high concentrations of methane ( CH4 ), The measurement accuracy of low concentrations of acetylene ( C2H2 ) in process gases containing ethylene ( C2H4 ) and/or ethane ( C2H6 ) can be improved.
  • the light source control unit 71 modulates the wavelength modulation range of the laser light so as to include wavelengths between 7.67 and 7.80 ⁇ m.
  • the light source control unit 71 preferably modulates the wavelength modulation range of the laser light so as to include a wavelength between 7.670 and 7.792 ⁇ m, more preferably a wavelength of 7.6704 ⁇ m or 7.7914 ⁇ m. .
  • the interfering effects of ethylene ( C2H4 ) and/or ethane ( C2H6 ) can be reduced, and high concentrations of ethylene ( C2H4 ) and/or ethane ( C 2 H 6 ) can be used to improve the measurement accuracy of the concentration of low-concentration methane (CH 4 ) in the process gas.
  • the light source controller 71 sets the wavelength modulation range of the laser light to include wavelengths between 8.10 and 8.14 ⁇ m. modulate to Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so that it preferably includes a wavelength between 8.107 and 8.139, more preferably a wavelength of 8.1073 ⁇ m or 8.1381 ⁇ m. .
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 8.10 and 8.13 ⁇ m. modulate. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so that it preferably includes a wavelength between 8.102 and 8.121, more preferably a wavelength of 8.1022 ⁇ m or 8.1206 ⁇ m. .
  • the light source control unit 71 adjusts the wavelength modulation range of the laser light to include wavelengths between 8.10 and 8.13 ⁇ m. modulate. Specifically, the light source control unit 71 modulates the wavelength modulation range of the laser light so as to include the wavelength of 8.1022 ⁇ m or 8.1206 ⁇ m.
  • the light source control unit 71 sets the wavelength modulation range of the laser light to include wavelengths between 8.46 and 8.60 ⁇ m. modulate as follows. Specifically, the light source control unit 71 preferably modulates the wavelength modulation range of the laser light to include a wavelength of 8.464 to 8.599 ⁇ m, more preferably a wavelength of 8.4647 ⁇ m or 8.5981 ⁇ m. .
  • the interfering effects of methane ( CH4 ) and/or ethane ( C2H6 ) can be reduced, and high concentrations of methane ( CH4 ) and/or ethane ( C2H6 ) can be reduced .
  • ) can be improved in measuring the concentration of high-concentration ethylene (C 2 H 4 ) in the process gas.
  • the light source control unit 71 sets the wavelength modulation range of the laser light to 6.09 ⁇ m between 6.13 ⁇ m and 6.14 ⁇ m. Modulate to include wavelengths between ⁇ 6.45 ⁇ m, 6.09-6.39 ⁇ m, or 6.41 ⁇ m-6.45 ⁇ m. Specifically, the light source control unit 71 controls the wavelength modulation range of the laser light to be preferably between 6.135 ⁇ m and 6.139 ⁇ m, or between 6.463 ⁇ m and 6.619 ⁇ m, more preferably between 6.1384 ⁇ m and 6.1384 ⁇ m.
  • the interfering effects of methane ( CH4 ) and/or ethylene ( C2H4 ) can be reduced, and high concentrations of methane ( CH4 ) and/or ethylene ( C2H4 ) can be reduced.
  • ) can be improved in measuring the concentration of high-concentration ethane (C 2 H 6 ) in the process gas.
  • the light source control unit 71 sets the wavelength modulation range of the laser light to between 6.06 and 6.25 ⁇ m. , 6.06-6.14 ⁇ m, 6.15-6.17 ⁇ m, 6.19-6.25 ⁇ m, or 8.62-9.09 ⁇ m.
  • the light source control unit 71 preferably determines that the wavelength modulation range of the laser light is between 6.141 and 6.153 ⁇ m, between 6.141 and 6.149 ⁇ m, between 6.150 and 6.153 ⁇ m, or Modulated to include wavelengths between 8.939 and 8.968 ⁇ m, more preferably 6.1450 ⁇ m, 6.1487 ⁇ m, 6.1496 ⁇ m, 8.9604 ⁇ m, 8.9473 ⁇ m, or 8.7671 ⁇ m.
  • the interfering effects of methane ( CH4 ) and/or ethylene ( C2H4 ) can be reduced, and high concentrations of methane ( CH4 ) and/or ethylene ( C2H4 ) can be reduced.
  • the light source control unit 71 sets the wavelength modulation range of the laser light to include wavelengths between 9.35 and 9.62 ⁇ m. modulate as follows. Specifically, the light source control unit 71 determines that the wavelength modulation range of the laser light preferably includes a wavelength between 9.477 and 9.526 ⁇ m, more preferably a wavelength of 9.5168 ⁇ m, 9.5042 ⁇ m, or 9.4861 ⁇ m. modulate as follows.
  • the temperature control section 72 controls the current source (or voltage source) of the temperature control section 3 by outputting a control signal for setting the temperature control section 3 to a predetermined target temperature. Thereby, the temperature control unit 3 controls the temperature of the semiconductor laser 2 to a predetermined target temperature.
  • control unit 7 of the present embodiment uses a correction parameter P( ⁇ ) (FIG. 6 ), and modulation correction indicating the relationship between the ambient temperature and the correction parameter P( ⁇ w) for correcting the modulation width deviation of the semiconductor laser 2 (see FIG. 6).
  • a relational data storage unit 73 for storing relational data is provided.
  • the relational data for wavelength correction is shown in FIG. 7(a). It is generated by obtaining a certain target temperature change amount in advance by experiment or calculation.
  • P( ⁇ ) is the target temperature change amount
  • T0 is the reference temperature (for example, room temperature (25° C.))
  • tk is the temperature at the ambient temperature T relative to the reference temperature T0 . This is a coefficient indicating the degree of influence of the target temperature change amount.
  • the relational data for wavelength correction may be in formula form as shown in FIG. 7(a), or may be in lookup table form as shown in FIG. 8(a).
  • the relation data for modulation correction is shown in FIG. 7(b). It is generated by obtaining a certain drive voltage (current) change amount in advance by experiment or calculation.
  • P( ⁇ w) is the amount of change in the drive voltage (current)
  • T 0 is the reference temperature (for example, room temperature (25° C.))
  • v k is the ambient temperature relative to the reference temperature T 0 . This is a coefficient indicating the degree of influence of the amount of change in drive voltage (current) at temperature T.
  • the modulation correction related data may be in the formula format as shown in FIG. 7(b) or in the lookup table format as shown in FIG. 8(b).
  • the temperature control unit 72 also corrects the wavelength deviation of the semiconductor laser 2 by changing the target temperature of the temperature control unit 3 using the temperature detected by the temperature sensor 4 and the relationship data for wavelength correction.
  • the light source control unit 71 also corrects the modulation width of the semiconductor laser 2 by changing the drive voltage or drive current of the semiconductor laser 2 using the temperature detected by the temperature sensor 4 and the relationship data for modulation correction. Specifically, the light source controller 71 corrects the modulation width by adjusting the amplitude or offset of the modulation voltage (modulation current) for modulating the wavelength.
  • the signal processing unit 8 includes a logarithm calculation unit 81, a correlation value calculation unit 82, a storage unit 83, a wavelength shift determination unit 84, a density calculation unit 85, and the like.
  • the logarithmic calculator 81 performs logarithmic calculation on the light intensity signal, which is the output signal of the photodetector 5 .
  • the function I(t) representing the change over time of the light intensity signal obtained by the photodetector 5 becomes like the "light intensity I(t)" in FIG. logarithmic intensity L(t)".
  • the correlation value calculator 82 calculates correlation values between an intensity-related signal related to the intensity of sample light and a plurality of predetermined feature signals.
  • a feature signal is a signal for extracting a waveform feature of an intensity-related signal by taking a correlation with the intensity-related signal.
  • the feature signal for example, a sine wave signal or various signals matching waveform features desired to be extracted from other intensity-related signals can be used.
  • the correlation value calculator 82 calculates correlation values between an intensity-related signal related to the intensity of the sample light and a plurality of feature signals with which a correlation different from a sine wave signal (sine function) is obtained with respect to the intensity-related signal. Calculate Here, the correlation value calculator 82 uses the logarithmically calculated light intensity signal (logarithmic intensity L(t)) as the intensity-related signal.
  • the correlation value calculator 82 calculates the correlation value Si It is desirable to calculate a corrected sample correlation value S′ i by subtracting a reference correlation value Ri , which is a correlation value between the intensity-related signal L 0 (t) of the reference light and the plurality of feature signals F i (t), from .
  • Ri a correlation value between the intensity-related signal L 0 (t) of the reference light and the plurality of feature signals F i (t)
  • the configuration may be such that the reference correlation value is not subtracted.
  • the acquisition timing of the reference light is simultaneous with the sample light, before or after the measurement, or any timing.
  • the reference light intensity-related signal or the reference correlation value may be acquired in advance and stored in the storage unit 83 .
  • a method of obtaining reference light simultaneously is, for example, to provide two photodetectors 5, split the modulated light from the semiconductor laser 2 by a beam splitter or the like, and use one for sample light measurement and the other for reference. It is conceivable to use it for optical measurement.
  • the correlation value calculator 82 uses, as the plurality of feature signals F i (t), a function that makes it easier to capture the waveform feature of the logarithmic intensity L(t) than a sine function.
  • a function based on a Lorentzian function close to the shape of the absorption spectrum as shown in the following equation (Equation 2) and a function based on the Lorentzian function It is conceivable to use a partial differential function of the deviation from the reference time position.
  • w is the Lorentz width
  • s is the shift from the reference time position of the absorption peak due to wavelength shift
  • A is an arbitrary constant
  • a 1 , A 2 and A 3 are F 1 (t)
  • This is an offset that adjusts F 2 (t) and F 3 (t) so that they become zero when integrated over the modulation period.
  • a function based on the Voigt function, a function based on the Gaussian function, or the like can be used instead of the function based on the Lorentz function.
  • the storage unit 83 stores the measurement obtained from each intensity-related signal and a plurality of feature signals F i (t) when the measurement target component and each interference component exist independently in the known wavelength shift amount of the reference light.
  • a single correlation value which is a correlation value per unit concentration of each of the target component and each interference component, is stored.
  • the plurality of feature signals F i (t) used to obtain this single correlation value are the same as the plurality of feature signals F i (t) used in the correlation value calculator 82 . In this manner, the storage unit 83 stores individual correlation values for each wavelength shift of various reference beams.
  • the storage unit 83 subtracts the reference correlation value from the correlation value when the measurement target component and each interference component exist alone, and then performs correction for conversion per unit concentration. It is desirable to store a single correlation value that As a result, the offset included in the single correlation value is removed, and the correlation value becomes proportional to the concentrations of the measurement target component and the interfering component, thereby reducing measurement errors. Note that the configuration may be such that the reference correlation value is not subtracted.
  • the wavelength shift determination unit 84 determines the wavelength shift amount W of the reference light from the light intensity signal, which is the output signal of the photodetector 5 .
  • the following procedure can be considered.
  • Each single correlation value s itar ( W k ) and s iint (W k ) are obtained in advance, and the sample correlation value obtained at the time of measurement and the single correlation value are compared and collated to determine the wavelength shift W of the reference light.
  • Specific comparison and collation methods include, for example, the nonlinear least-squares method involving iterative calculation using the steepest descent method, the Gauss-Newton method, the Levenberg-Marquardt method, and the like.
  • the number of required feature signals is equal to or greater than the sum of the number of types of measurement target components and the number of types of interference components plus one.
  • the reason for adding 1 is to correspond to the amount of wavelength shift, which is a parameter common to the light absorption spectrum of each component.
  • (b) Determine the wavelength shift amount W of the reference light using relational data indicating the relationship between the ambient temperature and the wavelength shift amount W and the measured ambient temperature.
  • the relational data is generated in advance by obtaining the wavelength shift W of the reference light for each ambient temperature of the light source 2 by experiment or calculation.
  • the concentration calculator 85 calculates the concentration of the component to be measured using the plurality of sample correlation values obtained by the correlation value calculator 82 .
  • the concentration calculator 85 calculates the plurality of sample correlation values obtained by the correlation value calculator 82 , the wavelength shift amount W determined by the wavelength shift determiner 84 , and the plurality of independent values stored in the storage unit 83 .
  • the concentration of the component to be measured is calculated based on the correlation value. More specifically, the density calculation unit 85 corrects and acquires the plurality of single correlation values stored in the storage unit 83 from the wavelength shift amount W obtained by the wavelength shift determination unit 84 . Then, the concentration calculation unit 85 calculates the plurality of sample correlation values obtained by the correlation value calculation unit 82, the corrected plurality of single correlation values corresponding to the determined wavelength shift amount W, the measurement target component and each interference. The concentration of the component to be measured is calculated by solving simultaneous equations consisting of the concentration of each component (see FIG. 9).
  • the sample gas contains one component to be measured and one interfering component.
  • the light source control unit 71 controls the semiconductor laser 2 to obtain the absorption spectrum of the component to be measured at a predetermined modulation frequency and modulation depth.
  • the wavelength of the laser light is modulated around the peak of .
  • the reference correlation value may be measured by performing the reference measurement using the zero gas.
  • a span gas (a gas with a known component concentration) into the cell 1 to perform a reference measurement.
  • This reference measurement is performed for each of a span gas in which the component to be measured exists alone and a span gas in which the interfering component alone exists.
  • the logarithmic calculator 61 receives each output signal of the photodetector 5 for each wavelength shift amount of the reference light and calculates the logarithmic intensity L(t). Then, the correlation value calculator 82 calculates the correlation values between the logarithmic intensity L(t) and the three feature signals F 1 (t), F 2 (t), and F 3 (t), and from the correlation values By dividing the result obtained by subtracting the reference correlation value by the concentration of the span gas, a single correlation value, which is the correlation value of each span gas per unit concentration, is calculated. Instead of calculating the single correlation value, the relationship between the span gas concentration and the correlation value of the span gas may be stored.
  • the correlation value calculator 82 calculates the correlation value S 1tar ( wk ) of the component to be measured. , S 2tar (w k ), S 3tar (w k ).
  • S 1tar (w k ) is the correlation value with the first feature signal
  • S 2tar (w k ) is the correlation value with the second feature signal
  • S 3tar (w k ) is , is the correlation value with the third feature signal.
  • the correlation value calculator 82 subtracts the reference correlation value Ri from the correlation values S 1tar (w k ), S 2tar (w k ), and S 3tar (w k ) to obtain the span gas concentration c of the component to be measured.
  • the single correlation values s 1tar (w k ), s 2tar (w k ), s 3tar (w k ) are calculated. This procedure is performed by changing the set temperature of the semiconductor laser 2 while sequentially changing the amount of wavelength deviation of the reference light (for example, from ⁇ 0.01 cm ⁇ 1 to +0.01 cm ⁇ 1 in increments of 0.001 cm ⁇ 1 ) . ) for each wavelength shift amount, and the relationship between the obtained single correlation value for each wavelength shift amount and the wavelength shift is stored.
  • the span gas concentration c tar of the component to be measured is input to the signal processing unit 8 in advance by a user or the like.
  • the correlation value calculator 82 calculates the correlation value S1int ( wk ) of the interference component. , S 2int (w k ), and S 3int (w k ).
  • S 1int (w k ) is the correlation value with the first feature signal
  • S 2int (w k ) is the correlation value with the second feature signal
  • S 3int (w k ) is , is the correlation value with the third feature signal.
  • the correlation value calculator 82 subtracts the reference correlation value Ri from the correlation values S 1int (w k ), S 2int (w k ), and S 3int (w k ) to obtain the span gas concentration c int of the interference component. to calculate the single correlation values s 1int (w k ), s 2int (w k ), s 3int (w k ).
  • This procedure is performed by changing the set temperature of the semiconductor laser 2 while sequentially changing the amount of wavelength deviation of the reference light (for example, from ⁇ 0.01 cm ⁇ 1 to +0.01 cm ⁇ 1 in increments of 0.001 cm ⁇ 1 ) . ) for each wavelength shift amount, and the relationship between the obtained single correlation value for each wavelength shift amount and the wavelength shift amount is stored.
  • the span gas concentration c int of the interference component is input to the signal processing unit 8 in advance by a user or the like.
  • Single correlation values s 1tar (w k ), s 2tar (w k ) , s 3tar (w k ), s 1int (w k ), s 2int (w k ) and s 3int (w k ) are stored in the storage unit 83 . Note that this reference measurement may be performed before product shipment, or may be performed periodically.
  • the light source controller 71 controls the semiconductor laser 2 to modulate the wavelength of the laser light with a predetermined modulation frequency and modulation depth centering on the peak of the absorption spectrum of the component to be measured.
  • the temperature control section 72 changes the target temperature of the temperature control section 3 using the detected temperature and the wavelength correction relationship data obtained by the temperature sensor 4 to correct the wavelength deviation of the semiconductor laser 2 .
  • the light source control unit 71 also corrects the modulation width of the semiconductor laser 2 by changing the drive voltage or drive current of the semiconductor laser 2 using the temperature detected by the temperature sensor 4 and the relationship data for modulation correction.
  • a sample gas is then introduced into the cell 1 by an operator or automatically, and a sample measurement is performed.
  • the logarithmic calculator 81 receives the output signal of the photodetector 3 and calculates the logarithmic intensity L(t). Then, the correlation value calculator 82 calculates sample correlation values S 1 , S 2 , S between the logarithmic intensity L(t) and the plurality of feature signals F 1 ( t), F 2 (t), F 3 (t). 3 is calculated, and sample correlation values S' 1 and S' 2 are calculated by subtracting the reference correlation value R i from the correlation value.
  • the wavelength shift determination unit 84 determines the wavelength shift amount W by the method described above.
  • the concentration calculator 85 calculates the wavelength shift amount W Determine the single correlation values s' 1tar , s' 2tar , s' 1int , s' 2int of the measured component and the interfering component corrected by .
  • a method of determination for example, a method using linear interpolation, quadratic interpolation, spline interpolation, or the like can be considered.
  • the density calculation unit 85 calculates the sample correlation values S′ 1 and S′ 2 corrected by the reference correlation values calculated by the correlation value calculation unit 82, and the corrected single correlation values s′ 1tar , s′ 2tar and s′ 1int . , s′ 2int , and the concentrations C tar and C int of the component to be measured and each interfering component, respectively (see FIG. 9).
  • Equation 4 By solving the n-dimensional simultaneous equations represented by this equation (Equation 4), it is possible to determine the concentration corrected for the interference effects of each gas of the measurement target component and the interfering component. Note that even if the sample does not contain any interfering components, it is possible to determine the concentration corrected for the interference effects of each gas of the measurement target component and the interfering component by solving the above n-dimensional simultaneous equations. can.
  • the wavelength modulation range can be accurately set when measuring the concentration of methanol (CH 3 OH) or ethanol (C 2 H 5 OH), and the concentrations thereof can be measured with accuracy.
  • the wavelength shift amount W of the reference light is determined by calculation, and the determined wavelength shift amount W is used to further correct the influence of the wavelength shift of the reference light. Since the concentration of the component to be measured is calculated, the change in the light absorption spectrum of the component to be measured caused by the wavelength shift of the reference light, which cannot be suppressed by physical wavelength shift correction, is corrected, and the concentration of the component to be measured is measured with even higher accuracy. can do.
  • the logarithmic intensity L(t), which is an intensity-related signal related to the intensity of the sample light, and the plurality of characteristic signals F i (t) for the logarithmic intensity L(t) ), and the concentration of the component to be measured is calculated using the plurality of calculated correlation values Si .
  • the concentration of the component to be measured can be measured with simple calculations without complicated spectral calculations. For example, several hundred data points are required for general spectrum fitting, but in the present invention, at most several to several tens of correlation values can be used to calculate concentrations with equivalent accuracy.
  • the load of arithmetic processing can be dramatically reduced, an advanced arithmetic processing device becomes unnecessary, the cost of the analysis device 100 can be reduced, and the size can be reduced.
  • the plurality of feature signals use signals that can obtain a correlation different from that of the sine wave signal, the accuracy is equal to or higher than that of an analyzer that performs concentration calculation by a method using conventional lock-in detection. It is possible to determine the concentration of the component to be measured.
  • the logarithmic calculator 61 in each of the above-described embodiments logarithmically calculates the light intensity signal of the photodetector 3.
  • the intensity of the sample light and the reference light It is also possible to calculate the logarithm (so-called absorbance) of the ratio to the intensity of the modulated light.
  • the logarithmic calculator 61 may calculate the logarithm of the intensity of the sample light, calculate the logarithm of the intensity of the reference light, and then subtract them to calculate the absorbance. After obtaining the ratio of the intensity of , the absorbance may be calculated by taking the logarithm of the ratio.
  • the correlation value calculator 62 in each of the above embodiments calculates the correlation value between the intensity-related signal and the feature signal, but instead calculates the inner product value of the intensity-related signal and the feature signal. good too.
  • the signal processing unit 8 of the analyzer 100 determines a broadening factor that indicates the rate of change in the optical absorption spectrum of the component to be measured or the interference component caused by the coexisting component contained in the sample.
  • a lighting factor determination unit 86 is provided.
  • the broadening factor determining section 86 determines a broadening factor FB that indicates the change rate of the light absorption spectra of the measurement target component and the interference component caused by the coexisting components contained in the sample. If the coexistence effect of the coexisting component on the interference component should also be considered, the broadening factor FB is added and determined for each component.
  • each single correlation value s itar ( p k ) and s iint (p k ) are obtained in advance, and the sample correlation value obtained at the time of measurement and the single correlation value are compared and collated to determine the broadening factor F B .
  • the single correlation value is converted and used using the pressure value in the cell and the relationship of the following formula (Equation 5).
  • the number of required feature signals is equal to or greater than the sum of the number of types of components to be measured, the number of types of interference components, and the number of types of broadening factors.
  • p is the sample pressure measured by the pressure sensor 7
  • F B is the broadening factor determined by the broadening factor determination unit 86
  • sij is the single correlation value at each pressure stored in the storage unit 63.
  • s' ij is the corrected single correlation value. Note that the above formula (Equation 5) is obtained by multiplying the single correlation value s ij (p) at the pressure p of the sample at the time of sample measurement by 1/FB times the single correlation value at the pressure obtained by multiplying the pressure by FB . indicates that the corrected single correlation value s' ij is obtained. If the interference component is also affected by broadening due to the coexisting component, the broadening factor of the interference component may be determined separately to correct the single correlation value of the interference component. This makes it possible to further improve the measurement accuracy.
  • the broadening factor FB is determined using the relationship data indicating the relationship between the concentration of the coexisting component and the broadening factor FB and the measured concentration of the coexisting component.
  • the relational data is generated in advance by determining the broadening factor FB for each concentration of the coexisting component by experiment or calculation.
  • the measured concentrations of the coexisting components may be those measured by the analyzer 100 of the present embodiment before coexistence influence correction, or the concentrations of the coexisting components may be measured using another analyzer.
  • the concentration calculator 65 calculates the concentration of the component to be measured using the plurality of sample correlation values obtained by the correlation value calculator 62 .
  • the density calculation unit 65 calculates the plurality of sample correlation values obtained by the correlation value calculation unit 62, the broadening factor FB determined by the broadening factor determination unit 64, and the plurality of correlation values stored in the storage unit 63.
  • the concentration of the component to be measured is calculated based on the single correlation value of .
  • the density calculator 65 corrects and acquires the plurality of single correlation values stored in the storage 63 from the broadening factor FB obtained by the broadening factor determiner 64 .
  • the concentration calculation unit 65 calculates the plurality of sample correlation values obtained by the correlation value calculation unit 62, the corrected plurality of single correlation values corresponding to the determined broadening factor FB , the component to be measured, and each The concentration of the component to be measured is calculated by solving simultaneous equations consisting of the concentrations of the interfering components.
  • the concentration calculator 65 calculates the single correlation value for the pressure p k in each cell stored in the storage unit 63, the pressure value p in the cell measured by the pressure sensor 7, and the broadening factor determination unit Using the broadening factor F B determined by 64 and the above equation (Equation 5), the single correlation values s′ 1tar , s′ of the component to be measured corrected for both the pressure in the cell and the broadening factor 2tar and the single correlation values s' 1int and s' 2int of the interference components corrected only for the pressure in the cell (assuming a broadening factor of 1).
  • a method of determination for example, a method using linear interpolation, quadratic interpolation, spline interpolation, or the like can be considered.
  • the density calculation unit 65 calculates the sample correlation values S′ 1 and S′ 2 corrected by the reference correlation values calculated by the correlation value calculation unit 62, and the corrected single correlation values s′ 1tar , s′ 2tar and s′. Solve the following simultaneous binary equations consisting of 1 int , s′ 2 int and the concentrations C tar , C int of the component to be measured and the interfering component, respectively.
  • the concentration C tar of the component to be measured from which the interference effect and the coexistence effect have been removed can be determined by a simple and reliable calculation of solving the simultaneous equations of the above equation (Equation 6).
  • the modulation width correction of the laser light source 2 of the present invention can suppress changes in the modulation width of the laser light source due to changes in the ambient temperature, and correct broadening due to coexistence effects. can be measured with higher accuracy.
  • the analysis device 100 may include a plurality of laser light sources 2 for irradiating the cells 2 with laser light and a plurality of temperature control units 3 corresponding thereto.
  • the plurality of laser light sources 2 correspond to, for example, the measurement target components exemplified in the above embodiments.
  • the plurality of laser light sources 2 are pulse-oscillated by the light source control unit 71 with the same oscillation cycle and different oscillation timings.
  • the control contents of the light source control section 71 and the temperature control section 72 for each laser light source 2 and each temperature control section 3 are the same as in the above embodiment.
  • the signal processing device 6 separates the signal of each of the plurality of laser light sources 2 from the light intensity signal obtained by the photodetector 5 , and uses the separated light absorption signal of each laser light source 2 to generate a signal for each laser light source 2 . Calculate the concentration of the corresponding component to be measured. Calculation of the concentration of the component to be measured by the signal processing unit 8 is the same as in the above embodiment.
  • the wavelength shift is corrected physically and the wavelength shift is corrected by calculation, but the wavelength shift may not be corrected by calculation.
  • the wavelength shift may be corrected by calculation without physically correcting the wavelength shift, or the wavelength shift may be corrected by calculation without physically correcting the wavelength shift.
  • the modulation width deviation may not be corrected.
  • the storage unit 83 stores the single correlation value corrected using the reference correlation value.
  • the unit 83 may be configured to subtract the reference correlation value from the uncorrected single correlation value and then obtain the corrected single correlation value converted per unit density.
  • the plurality of feature signals are not limited to the above embodiment, and may be different functions. Further, as the feature signal, for example, a function indicating a waveform (sample spectrum) of light intensity, logarithmic intensity, or absorbance obtained by flowing a span gas of known concentration may be used. Also, when measuring the concentration of one component to be measured, at least one characteristic signal is sufficient.
  • the number of single correlation values and sample correlation values larger than the number of gas kinds is obtained using feature signals of more than n kinds, It is also possible to create simultaneous equations with a greater number of elements than the number of gas species, and determine the concentration of each component by the least squares method. Become.
  • the signal processing unit of the embodiment uses an intensity-related signal related to the intensity of the sample light and a feature signal that provides a predetermined correlation with the intensity-related signal to obtain a concentration-dependent measurement of the component to be measured. function of the correlation value calculation unit for calculating the correlation value and the concentration calculation unit for calculating the concentration of the component to be measured using the correlation value obtained by the correlation value calculation unit. may be used.
  • the light source is not limited to a semiconductor laser, but may be any other type of laser, or any light source that is a single-wavelength light source that has a sufficient half-value width to ensure measurement accuracy and that can be wavelength-modulated. may
  • the concentration of at least one of nitrogen monoxide, nitrogen dioxide, nitrous oxide, ammonia, ethane, formaldehyde, acetaldehyde, sulfur dioxide, methane, methanol, or ethanol in combustion gas can be determined with accuracy. can be measured well.

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Abstract

La présente invention concerne un dispositif d'analyse et un procédé d'analyse, chacun desquels mesure la concentration d'un constituant devant être mesurée dans un gaz de combustion avec une précision élevée. Selon l'invention, la concentration en monoxyde d'azote est calculée sur la base de l'absorption du monoxyde d'azote de 5,24 à 5,26 µm ; la concentration en dioxyde d'azote est calculée sur la base de l'absorption du dioxyde d'azote de 6,14 à 6,26 µm ; la concentration en oxyde nitreux est calculée sur la base de l'absorption de l'oxyde nitreux de 7,84 à 7,91 µm ; la concentration en ammoniac est calculée sur la base de l'absorption de l'ammoniac de 9,38 à 9,56 µm ; la concentration en éthane est calculée sur la base de l'absorption de l'éthane de 3,33 à 3,36 µm ; la concentration en formaldéhyde ou acétaldéhyde est calculée sur la base de l'absorption du formaldéhyde ou de l'acétaldéhyde de 5,65 à 5,67 µm ; la concentration en dioxyde de soufre est calculée sur la base de l'absorption du dioxyde de soufre de 7,38 à 7,42 µm ; la concentration en méthane est calculée sur la base de l'absorption du méthane de 7,50 à 7,54 µm ; et la concentration en méthanol ou éthanol est calculée sur la base de l'absorption du méthanol ou de l'éthanol de 9,45 à 9,47 µm.
PCT/JP2022/043560 2021-11-25 2022-11-25 Dispositif d'analyse et procédé d'analyse WO2023095876A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995026497A1 (fr) * 1994-03-25 1995-10-05 Nippon Sanso Corporation Analyse de gaz par spectrochimie infrarouge et appareil utilise
JP2006052955A (ja) * 2004-08-09 2006-02-23 Japan Science & Technology Agency 気体中微量物質の濃度測定方法
WO2006085646A1 (fr) * 2005-02-14 2006-08-17 Japan Science And Technology Agency Appareil de mesure de la concentration gazeuse selon un procede de correlation gazeuse
JP2011191246A (ja) * 2010-03-16 2011-09-29 Fuji Electric Co Ltd レーザ式ガス分析計
JP2016090521A (ja) 2014-11-11 2016-05-23 株式会社島津製作所 ガス吸光度測定装置

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995026497A1 (fr) * 1994-03-25 1995-10-05 Nippon Sanso Corporation Analyse de gaz par spectrochimie infrarouge et appareil utilise
JP2006052955A (ja) * 2004-08-09 2006-02-23 Japan Science & Technology Agency 気体中微量物質の濃度測定方法
WO2006085646A1 (fr) * 2005-02-14 2006-08-17 Japan Science And Technology Agency Appareil de mesure de la concentration gazeuse selon un procede de correlation gazeuse
JP2011191246A (ja) * 2010-03-16 2011-09-29 Fuji Electric Co Ltd レーザ式ガス分析計
JP2016090521A (ja) 2014-11-11 2016-05-23 株式会社島津製作所 ガス吸光度測定装置

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